This invention relates in general to electrophotography and, more specifically, to a system for removing coating material from an end of a drum.
In electrophotography, coated substrates such as cylindrical photoreceptor drums (photoreceptors) are commonly used in copier, duplicator, facsimile and multifunctional machines. Photoreceptor embodiments include at least one coating of photosensitive material comprising a film forming polymer material, which can be formed on the photoreceptor by known techniques such as immersion or dip coating.
The peripheral ends of a coated photoreceptor are often used to engage members such as spacers, rollers, seals, developer housings, grounding devices and the like. If these members ride on a coated area of the drum, the coating material is rubbed off and the resulting debris can contaminate various components in the machine such as the cleaning system and any optical exposure systems employed in the machine. Also, the coating can interfere with devices that are designed to electrically ground the drum by contacting the outer surface at one end of the drum. Moreover, if the coating thickness is irregular because of poor removal techniques, spacing devices riding on the outside surface of the drum cannot maintain precise spacing between the drum and critical subsystems such as charging, developing, cleaning or other subsystems. Further, if coating material is present in the interior of the drums adjacent the ends of the drum, insertion of supporting end caps may be prevented or hindered. Also, uneven coating deposits in the interior of the drums can cause misalignment of the end caps which, in turn, can cause the drum to wobble during image cycling. The uncoated region at the end of the drum is also necessary to prevent delaminating or cracking of the organic layers at the base of the photoreceptor when the photoreceptor is cycled in an imaging machine. Thus, specified areas at both the outer and inner peripheral ends of a photoreceptor must be free of coating material.
The top of the drum may be maintained free of deposited coating by not immersing a small portion of the upper end of the drum into the coating solution. More specifically, the upper end of the photoreceptor drum can be kept free of coating material by orienting the drum vertically and dipping the drum into a bath of coating material to a predetermined depth which avoids complete immersion of the drum. However, the coating formed over the lower end of the photoreceptor must still be removed or prevented from depositing during dip coating.
U.S. Pat. No. 6,461,442 to Bush et al. for a “Process For Removing A Strip of Coating Material”, commonly assigned as the present application and herein incorporated by reference, teaches a two-piece cleaning foam to clean the bottom edge of a photoreceptor drum. The two-piece cleaning foam has a first piece of an inner foam and a second piece of an outer foam bonded together. The outer foam has an external drain groove to remove solvent and coating material from the drum. The two-piece foam requires precise alignment during fabrication and bonding of the two pieces. The two-piece foam has problems with formation of bubbles due to solvent flow around and through the two-piece foam. Bubbles reduce the efficiency of the removal of strip material for the photoreceptor drum.
It is, therefore, an object of the present invention to provide an improved edge cleaning system for electrophotographic imaging drums.
It is another object of the present invention to provide a one-piece sponge to clean the bottom edge of a photoreceptor drum.
It is yet another object of the present invention to provide improved solvent drainage in an edge cleaning system for electrophotographic imaging drums.